Delineating the role of chromosome 6 aberrations associated with the prognosis of primary uveal melanoma.


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Nawal Alshammari1,David Hammond1,Karen Sisley1
1University of Sheffield

Abstract

Background

Uveal melanomas (UM) are aggressive ocular tumours of adults that are typically characterized by chromosomal aberrations such as loss of 1p, 3, 6q, and gain 6p, and 8q. Of these monosomy 3 (M3) and 8q+ are powerful predictors of prognosis. The relationship of changes affecting chromosome 6 is however more ambivalent, having been linked to both good and poor prognosis. We hypothesized that different chromosome 6 alterations may have a variable impact on the prognosis of UM, and ultimately contain genes that contribute to the development and metastasis of this disease. It is likely that these changes can act as moderators to the tumour outcome.

Method

A series of 137 tumours primary UM were analysed for copy number variation using a custom high-resolution Comparative Genomic Hybridization Array (aCGH) provided by Agilent technologies. The series comprised patients collected over the period 1993 - 2014.

Results

Tumours were subdivided into those with alterations affecting just the short arm and/or the long arm of chromosome 6, and those UMs, which did not have involvement of chromosome 6. In total abnormalities for chromosome 6 affected 60% of UM. Further subdivision indicated there was a roughly equally split for abnormalities affecting just the p or q arm or both arms. In terms of prognosis the outcome for patients with 6p gain was similar whether in the form of an I(6)p or just 6p, but closer examination of the data suggested clear differences in the association with other changes, and potentially differences in the regions of 6p gained in subgroups of UM.

Conclusion

Initial findings suggest that different regions are targeted in the subgroups of UM affected with 6p gain, and that when considering the prognostic implications of 6p gain a number of qualifying alterations need also to be considered.